Pharmacokinetic and pharmacodynamic properties of EGFR inhibitors under clinical investigation

Molecular engineering of AIE-active boron clustoluminogens for enhanced boron neutron capture therapy

The development of boron delivery agents bearing an imaging capability is crucial for boron neutron capture therapy (BNCT), yet it has been rarely explored. Here we present a new type of boron delivery agent that integrates aggregation-induced emission (AIE)-active imaging and a carborane cluster for the first time. In doing so, the new boron delivery agents have been rationally designed by incorporating a high boron content unit of a carborane cluster, an erlotinib targeting unit towards lung cancer cells, and a donor-acceptor type AIE unit bearing naphthalimide. The new boron delivery agents demonstrate both excellent AIE properties for imaging purposes and highly selective accumulation in tumors. For example, at a boron delivery agent dose of 15 mg kg-1, the boron amount reaches over 20 μg g-1, and both tumor/blood (T/B) and tumor/normal cell (T/N) ratios reach 20-30 times higher than those required by BNCT. The neutron irradiation experiments demonstrate highly efficient tumor growth suppression without any observable physical tissue damage and abnormal behavior in vivo. This study not only expands the application scopes of both AIE-active molecules and boron clusters, but also provides a new molecular engineering strategy for a deep-penetrating cancer therapeutic protocol based on BNCT.

Preclinical Pharmacokinetics and Biodistribution of LR004, a Novel Antiepidermal Growth Factor Receptor Monoclonal Antibody

LR004 is a novel chimeric (human/mouse) monoclonal antibody developed for the treatment of advanced colorectal carcinoma with detectable epidermal growth factor receptor (EGFR) expression. We aimed to investigate the preclinical pharmacokinetics (PK) and in vivo biodistribution of LR004. The PK profiles of LR004 were initially established in rhesus monkeys. Subsequently, 125I radionuclide-labeled LR004 was developed and the biodistribution, autoradiography, and NanoSPECT/CT of 125I-LR004 in xenograft mice bearing A431 tumors were examined. The PK data revealed a prolonged half-life and nonlinear PK characteristics of LR004 within the dose range of 6-54 mg/kg. The radiochemical purity of 125I-LR004 was approximately 98.54%, and iodination of LR004 did not affect its specific binding activity to the EGFR antigen. In a classical biodistribution study, 125I-LR004 exhibited higher uptake in highly perfused organs than in poorly perfused organs. Prolonged retention properties of 125I-LR004 in tumors were observed at 4 and 10 days. Autoradiography and NanoSPECT/CT confirmed the sustained retention of 125I-LR004 at the tumor site in xenograft mice. These findings demonstrated the adequate tumor targeting capabilities of 125I-LR004 in EGFR-positive tumors, which may improve dosing strategies and future drug development.

Approaches Towards Better Immunosuppressive Agents

Several classes of compounds are applied in clinics due to their immunosuppressive properties in transplantology and the treatment of autoimmune diseases. Derivatives of mycophenolic acid, corticosteroids and chemotherapeutics bearing heterocyclic moieties like methotrexate, azathioprine, mizoribine, and ruxolitinib are active substances with investigated mechanisms of action. However, improved synthetic approaches of known drugs and novel derivatives are still being reported to attempt better accessibility and therapeutic properties. In this review article, we present the synthesis of the designed chemical structures based on recent literature reports concerning novel compounds as promising immunosuppressive drugs. Moreover, some of the discussed derivers revealed also other types of activities with prospective medicinal potential.

EpEX, the soluble extracellular domain of EpCAM, resists cetuximab treatment of EGFR-high head and neck squamous cell carcinoma

OBJECTIVES

Cetuximab (Cmab) is a molecularly targeted monoclonal antibody drug for head and neck squamous cell carcinoma (HNSC), although cetuximab resistance is a serious challenge. Epithelial cell adhesion molecule (EpCAM) is an established marker for many epithelial tumors, while the soluble EpCAM extracellular domain (EpEX) functions as a ligand for epidermal growth factor receptor (EGFR). We investigated the expression of EpCAM in HNSC, its involvement in Cmab action, and the mechanism by which soluble EpEX activated EGFR and played key roles in Cmab resistance.

MATERIALS AND METHODS

We first examined EPCAM expression in HNSCs and its clinical significance by searching gene expression array databases. We then examined the effects of soluble EpEX and Cmab on intracellular signaling and Cmab efficacy in HNSC cell lines (HSC-3 and SAS).

RESULTS

EPCAM expression was found to be enhanced in HNSC tumor tissues compared to normal tissues, and the enhancement was correlated with stage progression and prognosis. Soluble EpEX activated the EGFR-ERK signaling pathway and nuclear translocation of EpCAM intracellular domains (EpICDs) in HNSC cells. EpEX resisted the antitumor effect of Cmab in an EGFR expression-dependent manner.

CONCLUSION

Soluble EpEX activates EGFR to increase Cmab resistance in HNSC cells. The EpEX-activated Cmab resistance in HNSC is potentially mediated by the EGFR-ERK signaling pathway and the EpCAM cleavage-induced nuclear translocation of EpICD. High expression and cleavage of EpCAM are potential biomarkers for predicting the clinical efficacy and resistance to Cmab.

Constitutive Expression of a Cytotoxic Anticancer Protein in Tumor-Colonizing Bacteria

Bacterial cancer therapy is a promising next-generation modality to treat cancer that often uses tumor-colonizing bacteria to deliver cytotoxic anticancer proteins. However, the expression of cytotoxic anticancer proteins in bacteria that accumulate in the nontumoral reticuloendothelial system (RES), mainly the liver and spleen, is considered detrimental. This study examined the fate of the Escherichia coli strain MG1655 and an attenuated strain of Salmonella enterica serovar Gallinarum (S. Gallinarum) with defective ppGpp synthesis after intravenous injection into tumor-bearing mice (~10⁸ colony forming units/animal). Approximately 10% of the injected bacteria were detected initially in the RES, whereas approximately 0.01% were in tumor tissues. The bacteria in the tumor tissue proliferated vigorously to up to 10⁹ colony forming units/g tissue, whereas those in the RES died off. RNA analysis revealed that tumor-associated E. coli activated rrnB operon genes encoding the rRNA building block of ribosome needed most during the exponential stage of growth, whereas those in the RES expressed substantially decreased levels of this gene and were cleared soon presumably by innate immune systems. Based on this finding, we engineered ΔppGpp S. Gallinarum to express constitutively a recombinant immunotoxin comprising TGFα and the Pseudomonas exotoxin A (PE38) using a constitutive exponential phase promoter, the ribosomal RNA promoter rrnB P1. The construct exerted anticancer effects on mice grafted with mouse colon (CT26) or breast (4T1) tumor cells without any notable adverse effects, suggesting that constitutive expression of cytotoxic anticancer protein from rrnB P1 occurred only in tumor tissue.

Synthesis of New Bioactive Indolyl-1,2,4-Triazole Hybrids As Dual Inhibitors for EGFR/PARP-1 Targeting Breast and Liver Cancer Cells

Cancer is the most severe disease worldwide. Every year, tens of millions of people are diagnosed with cancer, and over half of those people will ultimately die from the disease. Hence, the discovery of new inhibitors for fighting cancer is necessary. As a result, new indolyl-triazole hybrids were synthesized to target breast and liver cancer cells. The synthetic strategy involves glycosylation of the 4-aryltriazolethiones 3a-b with acetyl-protected α-halosugars in the presence of K₂CO₃ in acetone to give a mixture of β-S-glycosides 6a-b, 7a-b, and β-N-glycosides 8a-b, 9a-b. Chemo-selective S-glycosylation was achieved using NaHCO₃ in ethanol. The migration of glycosyl moiety from sulfur to nitrogen (S → N glycosylmigration) was achieved thermally without any catalyst. Alkylation of the triazole-thiones with 2-bromoethanol and 1-bromopropan-2-ol in the presence of K₂CO₃ yielded the corresponding S-alkylated products. The synthesized compounds were tested for their cytotoxicity using an MTT assay and for apoptosis induction targeting PARP-1 and EGFR. Compounds 12b, 13a, and 13b exhibited cytotoxic activities with promising IC₅₀ values of 2.67, 6.21, 1.07 μM against MCF-7 cells and 3.21, 8.91, 0.32 μM against HepG2 cells compared to Erlotinib (IC₅₀ = 2.51, 2.91 μM, respectively) as reference drug. Interestingly, compounds 13b induced apoptosis in MCf-7 and HepG2 cells, arresting the cell cycle at the G2/M and S phases, respectively. Additionally, the dual enzyme inhibition seen in compound 13b against EGFR and PARP-1 is encouraging, with IC₅₀ values of 62.4 nM compared to Erlotinib (80 nM) and 1.24 nM compared to Olaparib (1.49 nM), respectively. The anticancer activity was finally validated using an in vivo SEC-cancer model; compound 13b improved both hematological and biochemical analyses inhibiting tumor proliferation by 66.7% compared to Erlotinib's 65.7%. So, compound 13b may serve as a promising anticancer activity through dual PARP-1/EGFR target inhibition.

Targeting EGFR in melanoma - The sea of possibilities to overcome drug resistance

Melanoma is considered one of the most aggressive skin cancers. It spreads and metastasizes quickly and is intrinsically resistant to most conventional chemotherapeutics, thereby presenting a challenge to researchers and clinicians searching for effective therapeutic strategies to treat patients with melanoma. The use of inhibitors of mutated serine/threonine-protein kinase B-RAF (BRAF), e.g., vemurafenib and dabrafenib, has revolutionized melanoma chemotherapy. Unfortunately, the response to these drugs lasts a limited time due to the development of acquired resistance. One of the proteins responsible for this process is epidermal growth factor receptor (EGFR). In this review, we summarize the role of EGFR signaling in the multidrug resistance of melanomas and discuss possible applications of EGFR inhibitors to overcome the development of drug resistance in melanoma cells during therapy.

Therapeutic approaches for the treatment of head and neck squamous cell carcinoma-An update on clinical trials

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common non-skin cancer with a tobacco consumption and infection with high-risk human papillomavirus (HPV) being major risk factors. Despite advances in numerous therapy modalities, survival rates for HNSCC have not improved considerably; a vast number of clinical outcomes have demonstrated that a combination strategy (the most well-known docetaxel, cisplatin, and 5-fluorouracil) is the most effective treatment choice. Immunotherapy that targets immunological checkpoints is being tested in a number of clinical trials, either alone or in conjunction with chemotherapeutic or targeted therapeutic drugs. Various monoclonal antibodies, such as cetuximab and bevacizumab, which target the EGFR and VEGFR, respectively, as well as other signaling pathway inhibitors, such as temsirolimus and rapamycin, are also being studied for the treatment of HNSCC. We have reviewed the primary targets in active clinical studies in this study, with a particular focus on the medications and drug targets used.

Development of Oral Tablet Formulation Containing Erlotinib: Randomly Methylated-β-cyclodextrin Inclusion Complex Using Direct Compression Method

Objectives

Erlotinib (ERL) is a tyrosine kinase inhibitor that has been used in the treatment of metastatic non-small cell lung cancer (NSCLC). However, its low aqueous solubility limits its absorption and oral bioavailability. To overcome these pharmacokinetic drawbacks, complexation of ERL can be applied. The aim of this study was to develop and characterize an oral tablet formulation containing ERL: Randomly methylated-β-cyclodextrin (RAMEB-CD) inclusion complex to enhance solubility and oral bioavailability of ERL.

Materials and Methods

An inclusion complex was prepared with RAMEB-CD using co-lyophilization technique. Structural characterization was performed using X-ray diffractometry and fourier-transform infrared spectroscopy. Tablet formulation of ERL: RAMEB-CD inclusion complex were prepared using direct compression technique. Tablet characteristics like hardness, diameter, thickness, friability, weight variability, disintegration and dissolution were evaluated. Flow properties of the powder were also determined.

Results

Characterization studies suggested that stable complexes between ERL and RAMEB-CD were obtained with co-lyophilization method. Tablet formulation using inclusion complex of ERL and RAMEB-CD with drug dose equivalent to 25 mg was successfully prepared using direct compression technique. Physical properties of the powder mixture were studied - angle of repose (°): 34.27±1.78; flow time: 2.2±0.4; HR: 1.05±0.02; compressibility index: 14.27±1.55. Moisture content (%) was found to be 0.27±0.05. The thickness, diameter and hardness values were 3.92±0.05 mm, 11.3±0.06 mm and 81.38±2.27 N, respectively. In uniformity of weight test, the average weight was 404.57±1.6 mg, with less than 5% deviation in 20 randomly selected tablets. Friability value was 0.27% and the disintegration time was found to be less than 15 min. Importantly, dissolution study showed that solubility of ERL was increased by complexation with RAMEB-CD. After 60 minutes, 99% of drug was released from the tablet formulation.

Conclusion

These results demonstrate that a new tablet formulation of ERL: RAMEB-CD inclusion complex could be an alternative approach to achieve increased dissolution and oral bioavailability of ERL for NSCLC treatment.

Pharmacokinetic properties and bioequivalence of gefitinib 250 mg in healthy Korean male subjects

Gefitinib is an anti-cancer drug used to treat non-small cell lung cancer. The objective of this study was to compare the pharmacokinetics and evaluate the bioequivalence of 2 orally administered gefitinib 250 mg tablets in healthy Korean subjects. A randomized, open-label, single-dose, crossover bioequivalence study was conducted. A total of 50 healthy male volunteers were randomized into 2 sequence groups. During each treatment, the subjects received the test or reference formulation of 250 mg gefitinib with a washout period of 21 days. The plasma samples were collected at pre-dose and up to 144 hours post-dose, and plasma drug concentrations were measured using validated liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated, and the formulations were considered as bioequivalent if the 90% confidence intervals (CIs) of the geometric mean ratios were within the bioequivalence limits of 0.8 to 1.25. Forty-one subjects completed the study and were included in the pharmacokinetic analysis. The 90% CIs of the geometric mean ratios of the test formulation to the reference formulation were 0.8115 to 0.9993 for maximum plasma concentration and 0.9119 to 1.0411 for area under the plasma concentration versus time curve from dosing to the last measurable concentration. There were no serious or unexpected adverse events during the study. In healthy Korean adult subjects, the test and reference formulations of gefitinib 250 mg had similar pharmacokinetic parameters and similar plasma concentration-time profiles. The test formulation of gefitinib met the regulatory criteria for assuming bioequivalence. Both formulations were safe and well-tolerated.

Duration of Oral Antibiotics Administration for Cetuximab-Induced Acneiform Eruption

BACKGROUND

Acneiform eruption is the most common cutaneous adverse event associated with cetuximab. As it can affect quality of life and adversely affect chemotherapy schedule, additional medical care is required.

OBJECTIVES

To investigate the adherence to and the duration of antibiotic administration to treat cetuximab-induced acneiform eruption.

METHODS

Medical data of patients who were referred to the Department of Dermatology were reviewed from January 2013 to June 2018. Dermatologists assessed the severity of acneiform eruption and prescribed tetracycline-class antibiotics according to the severity every 2 or 4 weeks. We investigated the duration and amount of oral antibiotic administration and analyzed the factors that may affect the control of acneiform eruption statistically.

RESULTS

A total of 207 of 267 patients referred to the Department of Dermatology showed acneiform eruption; 124 patients were treated with minocycline, 34 patients with doxycycline, 27 patients with both, and 22 patients with topical agents. The mean duration of oral antibiotic medication was 82.7 days. A statistical analysis of the factors that prolonged the use of antibiotics for more than 90 days showed that male and younger age were risk factors. Shorter time interval from starting cetuximab to starting antibiotics was associated with longer duration of antibiotic use, statistically.

CONCLUSIONS

Cetuximab-induced acneiform eruption can be well controlled with tetracycline-class antibiotics in about 3 months. It can last longer in male and younger patients. The sooner and the more severe it appears, the longer it can last.

Harnessing Omics Approaches on Advanced Preclinical Models to Discovery Novel Therapeutic Targets for the Treatment of Metastatic Colorectal Cancer

Metastatic colorectal cancer (mCRC) remains challenging because of the emergence of resistance mechanisms to anti-epidermal growth factor receptor (EGFR) therapeutics, so more effective strategies to improve the patients’ outcome are needed. During the last decade, the application of a multi-omics approach has contributed to a deeper understanding of the complex molecular landscape of human CRC, identifying a plethora of drug targets for precision medicine. Target validation relies on the use of experimental models that would retain the molecular and clinical features of human colorectal cancer, thus mirroring the clinical characteristics of patients. In particular, organoids and patient-derived-xenografts (PDXs), as well as genetically engineered mouse models (GEMMs) and patient-derived orthotopic xenografts (PDOXs), should be considered for translational purposes. Overall, omics and advanced mouse models of cancer represent a portfolio of sophisticated biological tools that, if optimized for use in concert with accurate data analysis, could accelerate the anticancer discovery process and provide new weapons against cancer. In this review, we highlight success reached following the integration of omics and experimental models; moreover, results produced by our group in the field of mCRC are also presented.

Molecular Targeting Therapy against EGFR Family in Breast Cancer: Progress and Future Potentials

The epidermal growth factor receptor (EGFR) family contains four transmembrane tyrosine kinases (EGFR1/ErbB1, Her2/ErbB2, Her3/ErbB3 and Her4/ErbB4) and 13 secreted polypeptide ligands. EGFRs are overexpressed in many solid tumors, including breast, pancreas, head-and-neck, prostate, ovarian, renal, colon, and non-small-cell lung cancer. Such overexpression produces strong stimulation of downstream signaling pathways, which induce cell growth, cell differentiation, cell cycle progression, angiogenesis, cell motility and blocking of apoptosis.The high expression and/or functional activation of EGFRs correlates with the pathogenesis and progression of several cancers, which make them attractive targets for both diagnosis and therapy. Several approaches have been developed to target these receptors and/or the EGFR modulated effects in cancer cells. Most approaches include the development of anti-EGFRs antibodies and/or small-molecule EGFR inhibitors. This review presents the state-of-the-art and future prospects of targeting EGFRs to treat breast cancer.

Design of Experiments (DoE) Approach to Optimize the Sustained Release Microparticles of Gefitinib

Background:

Gefitinib (GEF), the kinase inhibitor, is presently available as tablets to be taken orally in high doses of 250-500 mg per day due to its poor solubility. The solubility issues affect not only its onset of action but also the bioavailability. These drawbacks foresight the need to have an alternate dosage form, preferably a sustained release formulation.

Methods:

In the present study, microparticles were prepared by emulsion solvent evaporation using PLGA 50:50 (GEF-PLGA MP). A 32 factorial design was used to optimize the critical quality parameters to the set mean particle size in the range of 7.4±2.5 µm and entrapment efficiency of 80%. SEM microscopy of the prepared microparticles confirmed to have a spherical smooth shape. The GEFPLGA- MPs sustained the release of GEF for 72 hours. The first-order kinetics ruled the mechanism of drug release and was predicted to follow Fickian diffusion.

Result:

Anticancer efficacy was judged by the cytotoxicity studies using the L132 lung cancer cells. MTT assay showed 3-fold enhanced cytotoxicity of GEF loaded microparticles against L132 cells as compared to plain GEF.

Conclusion:

It was concluded that gefitinib can be efficiently loaded into the biodegradable polymer PLGA to provide sustained release of the drug.

Combination strategies based on epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors for cancer patients: Pooled analysis and subgroup analysis of efficacy and safety

BACKGROUND

Combination therapy based on epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) is an emerging trend in cancer treatment, but the clinical value of EGFR-TKIs combination therapy remains controversial. Thus, we conducted a comprehensive analysis of randomized controlled trials (RCTs) comparing EGFR-TKIs combination therapies with monotherapies, aiming to evaluate the safety and efficacy of EGFR-TKIs based combination therapy and to find a more beneficial combination strategy.

METHODS

We searched for clinical studies that evaluated EGFR-TKIs combination therapy in cancer. We extracted data from these studies to evaluate the relative risk (RR) of overall response rate (ORR) and grade 3/4 treatment-related adverse events (AEs), the hazard ratios (HRs) of overall survival (OS), and progression-free survival (PFS).

RESULTS

Fourteen RCTs were identified (n = 3774). Treatments included combinations of EGFR-TKIs and chemotherapy, combinations of EGFR-TKIs and radiotherapy, and combinations of EGFR-TKIs and bevacizumab. EGFR-TKIs combination therapies showed higher ORR [RR: 1.62; 95% confidence interval (95% CI):1.16-2.26; P = .005], PFS (HR: 0.76; 95% CI: 0.64-0.89; P = .001), and OS (HR: 0.88; 95% CI: 0.79-0.97; P = .013) values than monotherapies. However, higher grade 3/4 treatment-related AEs (RR: 1.79; 95% CI: 1.02-3.15; P = .000) were observed in combination therapy than in monotherapy.

CONCLUSION

Our pooled analysis and subgroup analysis results showed that the addition of chemotherapy to EGFR-TKIs better benefits PFS and safety. Adding bevacizumab was associated with better ORR and OS. The efficacy and safety of a bevacizumab-EGFR-TKIs-chemotherapy combination should be investigated further.

Low intensity focused ultrasound (LIFU) triggered drug release from cetuximab-conjugated phase-changeable nanoparticles for precision theranostics against anaplastic thyroid carcinoma

This study provides an efficient theranostic strategy for concurrent targeted ultrasound molecular imaging and effective synergistic antitumor therapy.

Effect of double mutations T790M/L858R on conformation and drug-resistant mechanism of epidermal growth factor receptor explored by molecular dynamics simulations

Epidermal growth factor receptor (EGFR) is one of the most promising targets for the treatment of cancers. Double mutations T790M/L858R lead to different degrees of drug resistance toward inhibitors. In this study, molecular dynamics (MD) simulations followed by principal component analysis are performed to study the conformational changes of EGFR induced by T790M/L858R. The results suggest that T790M/L858R cause obvious disturbance of the structural stability of EGFR. Molecular mechanics-Poisson Boltzmann surface area (MM-PBSA) and residue-based free energy decomposition methods are integrated to explore the drug-resistant mechanism of T790M/L858R toward inhibitors. The results show that the decrease in van der Waals interactions of inhibitors with the mutated EFGR relative to the wild-type (WT) one is the main force inducing drug resistance of T790M/L858R toward inhibitors TAK-285, while drug resistance toward W2P and HKI-272 is dominated by the decrease in van der Waals interactions and the increase in polar interactions. We expect that the information obtained from this study can aid rational design of effective drugs to relieve drug resistance of EGFR induced by T790M/L858R.

Phase 1 study of EGFR-antisense DNA, cetuximab, and radiotherapy in head and neck cancer with preclinical correlatives

BACKGROUND

Cetuximab combined with radiation therapy (RT) is an evidence-based treatment for locally advanced head and neck squamous cell carcinoma (HNSCC); however, locoregional failure remains the primary cause of cancer-related death in this disease. Intratumoral injection of epidermal growth factor receptor (EGFR)-antisense plasmid DNA (EGFR-AS) is safe and has been associated with promising lesional responses in patients who have recurrent/metastatic HNSCC. For the current study, the authors investigated the antitumor effects of cetuximab and EGFR-AS in preclinical HNSCC models and reported their phase 1 experience adding intratumoral EGFR-AS to cetuximab RT.

METHODS

Antitumor mechanisms were investigated in cell line and xenograft models. Phase 1 trial eligibility required stage IVA through IVC HNSCC and a measurable lesion accessible for repeat injections. Patients received standard cetuximab was for 9 weeks. EGFR-AS was injected weekly until they achieved a lesional complete response. RT was delivered by conventional fractionation for 7 weeks, starting at week 3. Research biopsies were obtained at baseline and week 2.

RESULTS

When added to cetuximab, EGFR-AS decreased cell viability and xenograft growth compared with EGFR-sense control, partially mediated by reduced EGFR expression. Six patients were enrolled in the phase 1 cohort. No grade 2 or greater EGFR-AS-related adverse events occurred. The best lesional response was a complete response (4 patients), and 1 patient each had a partial response and disease progression. EGFR expression decreased in 4 patients who had available paired specimens.

CONCLUSIONS

In preclinical models, dual EGFR inhibition with cetuximab and EGFR-AS enhanced antitumor effects. In a phase 1 cohort, intratumoral EGFR-AS injections, cetuximab, and RT were well tolerated. A phase 2 trial is needed to conduct an extended evaluation of safety and to establish efficacy.

Development and Clinical Indications of Cetuximab

Cetuximab is a chimeric immunoglobulin G1 monoclonal antibody that targets the extracellular domain of the epidermal growth factor receptor (EGFR) with high specificity and affinity. It competitively inhibits endogenous ligand binding and thereby inhibits subsequent EGFR activation. The EGFR signaling pathways regulate cell differentiation, proliferation, migration, angiogenesis and apoptosis, all of which become deregulated in cancer cells. EGFR is an important target for cancer therapy and many studies have demonstrated that cetuximab is active in several types of cancer, particularly colorectal and head and neck cancer. Cetuximab enhances the effects of many standard cytotoxic agents, including irinotecan, and in combination with chemotherapy it can elicit antitumor responses in tumors that previously failed to respond to that chemotherapy. Cetuximab also enhances radiation-induced apoptosis. On the basis of a pivotal European randomized study (the BOND study) and of 2 clinical studies conducted in the USA, cetuximab has been approved in combination with irinotecan for patients affected by EGFR-expressing metastatic colon cancer after failure with irinotecan. There have only been a few small phase II trials on first-line treatment in metastatic colorectal cancer, but the results suggest promising activity of cetuximab together with irinotecan or oxaliplatin. There is some evidence that additive efficacy can be achieved using EGFR inhibitors in combination with vascular endothelial growth factor receptor inhibitors such as bevacizumab. A correlation between response and the main toxicity (acne-like skin reaction) has been observed but is unclear. EGFR status as a specific marker for EGFR inhibitors is controversial. At the moment, EGFR expression does not appear to be a predictive factor for response to EGFR inhibitors.

Near infrared fluorescence imaging of EGFR expression in vivo using IRDye800CW-nimotuzumab

Nimotuzumab is a humanized anti-epidermal growth factor receptor (EGFR) monoclonal antibody that is approved in many countries for the treatment of EGFR-positive cancers. Near infrared (NIR) fluorescent dye-labeled antibodies represent an attractive class of image-guided surgical probes because of their high specificity, tumor uptake, and low dissociation from tumor cells that express the antigen. In this study, we developed a NIR fluorescent dye-labeled nimotuzumab immunoconjugate, IRDye800CW-nimotuzumab, and evaluated in vitro binding with EGFR-positive cells, in vivo tumor uptake by NIR fluorescent imaging, and ex vivo biodistribution. There was no difference in binding between nimotuzumab and IRDye800CW-nimotuzumab to EGFR-positive cells. In mice bearing EGFR-positive xenografts, IRDye800CW-nimotuzumab uptake peaked at 4 days post injection and slowly decreased thereafter with high levels of accumulation still observed at 28 days post injection. In EGFR-positive xenografts, IRDye800CW-nimotuzumab showed more than 2-fold higher uptake in tumors compared to IRDye800CW-cetuximab. In addition, liver uptake of IRDye800CW-nimotuzumab was two-fold lower than cetuximab. The lower liver uptake of IRDye800CW-nimotuzumab could have implications on the selected dose for clinical trials of the immunoconjugate. In summary, this study shows that nimotuzumab is a good candidate for NIR fluorescent imaging and image-guided surgery.

Structure-based pharmacophore design and virtual screening for novel potential inhibitors of epidermal growth factor receptor as an approach to breast cancer chemotherapy

Cancer cells are described with features of uncontrolled growth, invasion and metastasis. The epidermal growth factor receptor subfamily of tyrosine kinases (EGFR-TK) plays a crucial regulatory role in the control of cellular proliferation and progression of various cancers. Therefore, its inhibition might lead to the discovery of a new generation of anticancer drugs. In the present study, structure-based pharmacophore modeling, molecular docking and molecular dynamics simulations were applied to identify potential hits, which exhibited good inhibition on the proliferation of MCF-7 breast cancer cell line and favorable binding interactions on EGFR-TK. Selected compounds were examined for their anticancer activity against the Michigan Cancer Foundation-7 (MCF-7) breast cancer cell line which overexpresses EGFR using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay. Compounds 1 and 2, with an isoindoline-1-one core, induced significant inhibition of breast cancer cells proliferation with IC[Formula: see text] values 327 and 370 nM, respectively.

Anti-tumor activity of an immunotoxin (TGFα-PE38) delivered by attenuated Salmonella typhimurium

The anticancer strategy underlying the use of immunotoxins is as follows: the cancer-binding domain delivers the toxin to a cancer cell, after which the toxin enters and kills the cell. TGFα-PE38 is an immunotoxin comprising transforming growth factor alpha (TGFα), a natural ligand of epidermal growth factor receptor (EGFR), and a modified Pseudomonas exotoxin A (PE38) lacking N terminal cell-binding domain, a highly potent cytotoxic protein moiety. Tumor cells with high level of EGFR undergo apoptosis upon treatment with TGFα-PE38. However, clinical trials demonstrated that this immunotoxin delivered by an intracerebral infusion technique has only a limited inhibitory effect on intracranial tumors mainly due to inconsistent drug delivery. To circumvent this problem, we turned to tumor-seeking bacterial system. Here, we engineered Salmonella typhimurium to selectively express and release TGFα-PE38. Engineered bacteria were administered to mice implanted with mouse colon or breast tumor cells expressing high level of EGFR. We observed that controlled expression and release of TGFα-PE38 from intra-tumoral Salmonellae by either an engineered phage lysis system or by a bacterial membrane transport signal led to significant inhibition of solid tumor growth. These results demonstrated that delivery by tumor-seeking bacteria would greatly augment efficacy of immunotoxin in cancer therapeutics.

Optimal Affinity of a Monoclonal Antibody: Guiding Principles Using Mechanistic Modeling

Affinity optimization of monoclonal antibodies (mAbs) is essential for developing drug candidates with the highest likelihood of clinical success; however, a quantitative approach for setting affinity requirements is often lacking. In this study, we computationally analyzed the in vivo mAb-target binding kinetics to delineate general principles for defining optimal equilibrium dissociation constant ([Formula: see text]) of mAbs against soluble and membrane-bound targets. Our analysis shows that in general [Formula: see text] to achieve 90% coverage for a soluble target is one tenth of its baseline concentration ([Formula: see text]), and is independent of the dosing interval, target turnover rate or the presence of competing ligands. For membrane-bound internalizing targets, it is equal to the ratio of internalization rate of mAb-target complex and association rate constant ([Formula: see text]). In cases where soluble and membrane-bound forms of the target co-exist, [Formula: see text] lies within a range determined by the internalization rate ([Formula: see text]) of the mAb-membrane target complex and the ratio of baseline concentrations of soluble and membrane-bound forms ([Formula: see text]). Finally, to demonstrate practical application of these general rules, we collected target expression and turnover data to project [Formula: see text] for a number of marketed mAbs against soluble (TNFα, RANKL, and VEGF) and membrane-bound targets (CD20, EGFR, and HER2).

Expression of p53, p16, cyclin D1, epidermal growth factor receptor and Notch1 in patients with temporal bone squamous cell carcinoma

BACKGROUND

The aim of this study was to investigate the expression of p53, p16, cyclin D1, epidermal growth factor receptor (EGFR) and Notch1 in temporal bone squamous cell carcinoma (TBSCC) tissue samples by immunohistochemistry (IHC), and to evaluate the association between these biomarkers and clinicopathological features.

METHODS

We performed a retrospective, single-institution review of 30 TBSCC patients treated with curative intent between April 2006 and March 2015. All tissue samples were obtained from pretreatment biopsy specimens or surgical specimens and using IHC staining.

RESULTS

Ten patients were categorized as T1, seven as T2, five as T3 and eight as T4. Nine patients had clinically positive lymph node metastasis. The positive expression of p53 and EGFR was significantly associated with T classification (P = 0.042 and P = 0.0039). EGFR expression was significantly more frequent in patients with positive lymph node metastasis compared with patients without node involvement (P = 0.017). In the analysis of the association between protein expression by IHC staining and prognosis, the positive expression of EGFR and Notch1 was significantly correlated with poor survival outcomes in TBSCC (P = 0.015 and P = 0.025) CONCLUSION: Overexpression of p53 and EGFR may be valuable biomarkers for identifying individuals at high risk of developing tumors in TBSCC. Furthermore, the positive expression of EGFR was significantly associated with poor survival outcome. Anti-EGFR therapy has potential for use as the treatment modality of choice for advanced-stage TBSCC as well as other head and neck squamous cell carcinomas.

Systematic review and meta-analysis of the risk of severe and life-threatening thromboembolism in cancer patients receiving anti-EGFR monoclonal antibodies (cetuximab or panitumumab)

Cancer-associated thromboembolism is a substantial problem in clinical practice. An increase in the level of fibrinopeptide A (a substance associated with hypercoagulable states) has been observed in humans exposed to fluorouracil. Anti-EGFR monoclonal antibodies cetuximab and panitumumab, which are now widely used in patients with metastatic colorectal cancer, could prolong the uncovering of endothelial structures resulting from flouorouracil or other co-administered agents, thus favouring several factors leading to thromboembolism. We performed a systematic review and meta-analysis of randomised, controlled trials assessing whether cancer patients receiving anti-EGFR monoclonal antibodies cetuximab and panitumumab are at increased risk of thromboembolic events. We searched electronic databases (Medline, Embase, Web of Science, Central) and reference lists. Phase II/III randomised, controlled trials comparing standard anti-cancer regimens with or without anti-EGFR monoclonal antibodies and reporting serious venous thromboembolic events were included in the analysis. Seventeen studies (12,870 patients) were considered for quantitative analysis. The relative risk (RR) for venous thromboembolism (18 comparisons) was 1.46 (95% CI 1.26 to 1.69); the RR of pulmonary embolism, on the basis of eight studies providing nine comparisons, was 1.55 (1.20 to 2.00). Cancer patients receiving anti-EGFR monoclonal antibodies-containing regimens are approximately 1.5 times more likely to experience venous or pulmonary embolism, compared to those treated with the same regimens without anti-EGFR monoclonal antibodies. Clinicians should consider patient's baseline thromboembolic risk when selecting regimens that include cetuximab or panitumumab. Potential non-reporting of these important adverse events remains a concern. PROSPERO registration number is CRD42014009165.

Tyrosine dephosphorylation enhances the therapeutic target activity of epidermal growth factor receptor (EGFR) by disrupting its interaction with estrogen receptor (ER)

Protein-protein interactions can increase or decrease its therapeutic target activity and the determining factors involved, however, are largely unknown. Here, we report that tyrosine-dephosphorylation of epidermal growth factor receptor (EGFR) increases its therapeutic target activity by disrupting its interaction with estrogen receptor (ER). Protein tyrosine phosphatase H1 (PTPH1) dephosphorylates the tyrosine kinase EGFR, disrupts its interaction with the nuclear receptor ER, and increases breast cancer sensitivity to small molecule tyrosine kinase inhibitors (TKIs). These effects require PTPH1 catalytic activity and its interaction with EGFR, suggesting that the phosphatase may increase the sensitivity by dephosphorylating EGFR leading to its dissociation with ER. Consistent with this notion, a nuclear-localization defective ER has a higher EGFR-binding activity and confers the resistance to TKI-induced growth inhibition. Additional analysis show that PTPH1 stabilizes EGFR, stimulates the membranous EGFR accumulation, and enhances the growth-inhibitory activity of a combination therapy of TKIs with an anti-estrogen. Since EGFR and ER both are substrates for PTPH1 in vitro and in intact cells, these results indicate that an inhibitory EGFR-ER protein complex can be switched off through a competitive enzyme-substrate binding. Our results would have important implications for the treatment of breast cancer with targeted therapeutics.

Combination of erlotinib and EGCG induces apoptosis of head and neck cancers through posttranscriptional regulation of Bim and Bcl-2

Combinatorial approaches using two or more compounds are gaining increasing attention for cancer therapy. We have previously reported that the combination of the EGFR-TKI erlotinib and epigallocatechin-3-gallate (EGCG) exhibited synergistic chemopreventive effects in head and neck cancers by inducing the expression of Bim, p21, p27, and by inhibiting the phosphorylation of ERK and AKT and expression of Bcl-2. In the current study, we further investigated the mechanism of regulation of Bim, Bcl-2, p21 and p27, and their role in apoptosis. shRNA-mediated silencing of Bim significantly inhibited apoptosis induced by the combination of erlotinib and EGCG (p = 0.005). On the other hand, overexpression of Bcl-2 markedly protected cells from apoptosis (p = 0.003), whereas overexpression of constitutively active AKT only minimally protected cells from apoptosis induced by the combination of the two compounds. Analysis of mRNA expression by RT-PCR revealed that erlotinib, EGCG and their combination had no significant effects on the mRNA expression of Bim, p21, p27 or Bcl-2 suggesting the post-transcriptional regulation of these molecules. Furthermore, we found that erlotinib or the combination of EGCG and erlotinib inhibited the phosphorylation of Bim and stabilized Bim after inhibition of protein translation by cycloheximide. Taken together, our results strongly suggest that the combination of erlotinib and EGCG induces apoptosis of SCCHN cells by regulating Bim and Bcl-2 at the posttranscriptional level.

The retinoic acid derivative, ABPN, inhibits pancreatic cancer through induction of Nrdp1

Combination chemotherapy for the treatment of pancreatic cancer commonly employs gemcitabine with an EGFR inhibitor such as erlotinib. Here, we show that the retinoic acid derivative, ABPN, exhibits more potent anticancer effects than erlotinib, while exhibiting less toxicity toward noncancerous human control cells. Low micromolar concentrations of ABPN induced apoptosis in BxPC3 and HPAC pancreatic cancer cell lines, concomitant with a reduction in phosphorylated EGFR as well as decreased ErbB3, Met and BRUCE protein levels. The degradation of ErbB3 is a result of proteasomal degradation, possibly due to the ABPN-dependent upregulation of Nrdp1. Administration of ABPN showed significant reductions in tumor size when tested using a mouse xenograft model, with higher potency than erlotinib at the same concentration. Analysis of the tumors demonstrated that ABPN treatment suppressed ErbB3 and Met and induced Nrdp1 in vivo. The data suggest that ABPN may be more suitable in combination chemotherapy with gemcitabine than the more widely used EGFR inhibitor, erlotinib.

Loss-of-Function PTPRD Mutations Lead to Increased STAT3 Activation and Sensitivity to STAT3 Inhibition in Head and Neck Cancer

BACKGROUND

Protein tyrosine phosphatase receptor type D (PTPRD) is a putative tumor suppressor in several cancers including head and neck squamous cell carcinoma (HNSCC). STAT3 is a frequently hyperactivated oncogene in HNSCC. As STAT3 is a direct substrate of PTPRD, we sought to determine the genetic or epigenetic alterations of PTPRD that contribute to overactive STAT3 in HNSCC.

METHODS

We analyzed data from The Cancer Genome Atlas (TCGA) and our previous whole-exome sequencing study and summarized the mutation, methylation, and copy number status of PTPRD in HNSCC and other cancers. In vitro studies involved standard transfection and MTT protocols, as well as methylation-specific PCR.

RESULTS

Our findings indicate that PTPRD mutation, rather than methylation or copy number alteration, is the primary mechanism by which PTPRD function is lost in HNSCC. We demonstrate that overexpression of wild-type PTPRD in HNSCC cells significantly inhibits growth and STAT3 activation while PTPRD mutants do not, suggesting that mutation may lead to loss of function and subsequent hyper-phosphorylation of PTPRD substrates, especially STAT3. Importantly, we determined that HNSCC cells harboring an endogenous PTPRD mutation are more sensitive to STAT3 blockade than PTPRD wild-type cells. We additionally found that PTPRD mRNA expression does not correlate with pSTAT3 expression, suggesting that alterations that manifest through altered mRNA expression, including hypermethylation and gene copy number alterations, do not significantly contribute to STAT3 overactivation in HNSCC.

CONCLUSION

PTPRD mutation, but not methylation or copy number loss, may serve as a predictive biomarker of sensitivity to STAT3 inhibitors in HNSCC.

Isolation and Characterization of a Monobody with a Fibronectin Domain III Scaffold That Specifically Binds EphA2

Monobodies are binding scaffold proteins originating from a human fibronectin domain III (Fn3) scaffold that can be easily engineered with specificity and affinity. Human EphA2 (hEphA2) is an early detection marker protein for various tumors including lung, breast, and colon cancer. In this study, we isolated two hEphA2-specific monobodies (E1 and E10) by screening a yeast surface display library. They showed the same amino acid sequence except in the DE loop and had high affinity (~2 nM Kd) against hEphA2. E1 bound only hEphA2 and mEphA2, although it bound hEphA2 with an affinity 2-fold higher than that of mEphA2. However, E10 also bound the mEphA6 and mEphA8 homologs as well as hEphA2 and mEphA2. Thus, E1 but not E10 was highly specific for hEphA2. E1 specifically bound human cells and xenograft tumor tissues expressing hEphA on the cell surface. In vivo optical imaging showed strong targeting of Cy5.5-labeled E1 to mouse tumor tissue induced by PC3 cells, a human prostate cancer cell line that expresses a high level of hEphA2. In conclusion, the highly specific monobody E1 is useful as a hEphA2 probe candidate for in vivo diagnosis and therapy.

Epidermal growth factor receptor inhibition by anti-CD147 therapy in cutaneous squamous cell carcinoma

BACKGROUND

Advanced cutaneous squamous cell carcinoma (SCC) is an uncommon and aggressive malignancy. As a result, there is limited understanding of its biology and pathogenesis. CD147 and epidermal growth factor receptor (EGFR) have been identified as oncologically important targets, but their relationship remains undefined in cutaneous SCC.

METHODS

Multiple cutaneous SCC cell lines (Colo-16, SRB-1, and SRB-12), were treated in vitro with a range of chimeric anti-CD147 monoclonal antibody (mAb) (0, 50, 100, and 200 µg/mL) or transfected with a small interfering RNA against CD147 (SiCD147). Cell proliferation, migration (scratch wound healing assay), and protein expression was then assessed. In vivo, Colo-16 flank xenografts were treated anti-CD147 mAb (150 µg i.p. triweekly).

RESULTS

After treatment with anti-CD147 (200 µg/mL), there was a significant decrease in proliferation for all cell lines relative to controls (p < .005). In addition, treatment with anti-CD147 (200 µg/mL) resulted in decreased cell migration for all cell lines, with an average of 43% reduction in closure compared to controls (p < .001). Colo-16 SiCD147 expression demonstrated similar reduction in proliferation and wound closure. Anti-CD147 antibody therapy and siRNA mediated reduction in CD147 expression were both found to decrease protein expression of EGFR, which correlated with a reduction in downstream total and phosphorylated protein kinase B (pAKT). Tumor growth in vivo was reduced for both the anti-CD147 treatment group and the SiCD147 group relative to controls.

CONCLUSION

Inhibition and downregulation of CD147 in cutaneous SCC resulted in suppression of the malignant phenotype in vitro and in vivo, which may be mediated in part by an alteration in EGFR expression. As a result, CD147 may serve as a potential therapeutic target for advanced cutaneous SCC.

Ligand-conjugated pH-sensitive polymeric micelles for the targeted delivery of gefitinib in lung cancers

The aim of the present study was to investigate the tumor targeting potential of a mannose-conjugated pH-sensitive nanosystem for the effective delivery of gefitinib (Gnb) to lung cancers.

The modulation of ABC transporter-mediated multidrug resistance in cancer: a review of the past decade

ATP-binding cassette (ABC) transporters represent one of the largest and oldest families of membrane proteins in all extant phyla from prokaryotes to humans, which couple the energy derived from ATP hydrolysis essentially to translocate, among various substrates, toxic compounds across the membrane. The fundamental functions of these multiple transporter proteins include: (1) conserved mechanisms related to nutrition and pathogenesis in bacteria, (2) spore formation in fungi, and (3) signal transduction, protein secretion and antigen presentation in eukaryotes. Moreover, one of the major causes of multidrug resistance (MDR) and chemotherapeutic failure in cancer therapy is believed to be the ABC transporter-mediated active efflux of a multitude of structurally and mechanistically distinct cytotoxic compounds across membranes. It has been postulated that ABC transporter inhibitors known as chemosensitizers may be used in combination with standard chemotherapeutic agents to enhance their therapeutic efficacy. The current paper reviews the advance in the past decade in this important domain of cancer chemoresistance and summarizes the development of new compounds and the re-evaluation of compounds originally designed for other targets as transport inhibitors of ATP-dependent drug efflux pumps.

Effect of antigen-dependent clearance on pharmacokinetics of anti-heparin-binding EGF-like growth factor (HB-EGF) monoclonal antibody

Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family and is an important therapeutic target in some types of human cancers. KM3566 is a mouse anti-HB-EGF monoclonal antibody that neutralizes HB-EGF activity by inhibiting the binding of HB-EGF to its receptors. Based on the results of our pharmacokinetics study, a humanized derivative antibody, KHK2866, is rapidly cleared from serum and shows nonlinear pharmacokinetics in cynomolgus monkeys. In this study, we examined the antigen-dependent clearance of an anti-HB-EGF monoclonal antibody in vivo and in vitro in order to pharmacokinetically explain the rapid elimination of KHK2866. We revealed tumor size-dependent clearance of KM3566 in in vivo studies and obtained good fits between the observed and simulated concentrations of KM3566 based on the two-compartment with a saturable route of clearance model. Furthermore, in vivo imaging analyses demonstrated tumor-specific distribution of KM3566. We then confirmed rapid internalization and distribution to lysosome of KM3566 at a cellular level. Moreover, we revealed that the amounts of HB-EGF on cell surface membrane were maintained even while HB-EGF was internalized with KM3566. Recycled or newly synthesized HB-EGF, therefore, may contribute to a consecutive clearance of KM3566, which could explain a rapid clearance from serum. These data suggested that the rapid elimination in pharmacokinetics of KM3566 is due to antigen-dependent clearance. Given that its antigen is expressed in a wide range of normal tissue, it is estimated that the rapid elimination of KHK2866 from cynomolgus monkey serum is caused by antigen-dependent clearance.

Tyrosine kinase inhibitors as reversal agents for ABC transporter mediated drug resistance

Tyrosine kinases (TKs) play an important role in pathways that regulate cancer cell proliferation, apoptosis, angiogenesis and metastasis. Aberrant activity of TKs has been implicated in several types of cancers. In recent years, tyrosine kinase inhibitors (TKIs) have been developed to interfere with the activity of deregulated kinases. These TKIs are remarkably effective in the treatment of various human cancers including head and neck, gastric, prostate and breast cancer and several types of leukemia. However, these TKIs are transported out of the cell by ATP-binding cassette (ABC) transporters, resulting in development of a characteristic drug resistance phenotype in cancer patients. Interestingly, some of these TKIs also inhibit the ABC transporter mediated multi drug resistance (MDR) thereby; enhancing the efficacy of conventional chemotherapeutic drugs. This review discusses the clinically relevant TKIs and their interaction with ABC drug transporters in modulating MDR.

Resistance of oral squamous cell carcinoma cells to cetuximab is associated with EGFR insensitivity and enhanced stem cell-like potency

Cetuximab, a specific anti-epidermal growth factor receptor (EGFR) monoclonal antibody, is used in cancer treatment. Although development of resistance to cetuximab is well recognized, the underlying mechanisms remain unclear. In the present study, we characterized cetuximab-resistant oral squamous cell carcinoma (OSCC) cell lines. The human OSCC cell lines HSC3, HSC4 and SAS were used in the present study. Effects of inhibitors including cetuximab on growth in cells were assessed by MTT assays. Southern blotting and immunofluorescence analysis were performed to examine protein expression and localization. Sphere formation was used to characterize stem cell-like properties. Floating aggregation culture was used for anchorage-independent growth. Cetuximab inhibited proliferation of HSC3 and HSC4 cells, but not SAS cells. Proliferation of all three cell lines was inhibited by the EGFR/ErbB2/ErbB4 inhibitor II. The EGFR inhibitor AG1478 strongly inhibited HSC3 and HSC4 proliferation, but that of SAS cells only moderately. EGFR proteins were localized on cell surface and phosphorylated in all three cell lines. SAS cells could proliferate in serum-free monolayer culture and formed spheres from single cells in floating culture. HSC3 and HSC4 could not proliferate under serum-free culture conditions and could not form spheres. Growth of SAS spheres required serum, and was inhibited by both AG1478 and cetuximab. Thus, cetuximab-resistant SAS cells not only engaged in EGFR-independent growth but also exhibited stem cell-like properties. However, growth was EGFR-dependent in aggregation culture, and the SAS cell aggregates became cetuximab-sensitive. This suggests that cetuximab sensitivity is not only cell-type-dependent but is also affected by the growth microenvironment.

Quantification and kinetic analysis of Grb2-EGFR interaction on micro-patterned surfaces for the characterization of EGFR-modulating substances

The identification of the epidermal growth factor receptor (EGFR) as an oncogene has led to the development of several anticancer therapeutics directed against this receptor tyrosine kinase. However, drug resistance and low efficacy remain a severe challenge, and have led to a demand for novel systems for an efficient identification and characterization of new substances. Here we report on a technique which combines micro-patterned surfaces and total internal reflection fluorescence (TIRF) microscopy (μ-patterning assay) for the quantitative analysis of EGFR activity. It does not simply measure the phosphorylation of the receptor, but instead quantifies the interaction of the key signal transmitting protein Grb2 (growth factor receptor-bound protein 2) with the EGFR in a live cell context. It was possible to demonstrate an EGF dependent recruitment of Grb2 to the EGFR, which was significantly inhibited in the presence of clinically tested EGFR inhibitors, including small tyrosine kinase inhibitors and monoclonal antibodies targeting the EGF binding site. Importantly, in addition to its potential use as a screening tool, our experimental setup offers the possibility to provide insight into the molecular mechanisms of bait-prey interaction. Recruitment of the EGFR together with Grb2 to clathrin coated pits (CCPs) was found to be a key feature in our assay. Application of bleaching experiments enabled calculation of the Grb2 exchange rate, which significantly changed upon stimulation or the presence of EGFR activity inhibiting drugs.

Is biomarker research advancing in the era of personalized medicine for head and neck cancer?

Recent progress in molecular biology and translational research has initiated an era of personalized medicine in head and neck clinical oncology. The genetic information defined by biomarker analysis in tumors and individuals is indispensable for the administration of molecular targeting agents. The epidermal growth factor receptor (EGFR) signaling pathway is an important therapeutic target in head and neck squamous cell carcinoma (HNSCC). The use of an anti-EGFR monoclonal antibody (mAb), cetuximab (Cmab), has been approved for the treatment of patients with head and neck cancer. Although KRAS mutation has been established as a potential biomarker for predicting the efficacy of anti-EGFR mAb in colorectal cancer, little is known about predictive markers for Cmab in head and neck cancer. Optimal predictive and prognostic markers as well as safety markers are required to promote the appropriate clinical use of Cmab and to determine malignant phenotypes in head and neck cancer. This article first reviews the role of EGFR signaling in HNSCC. The article then focuses on Ras/Raf/Mek/Erk and PTEN/PI3K/Akt signaling pathways as predictive markers for Cmab. Subsequently, the molecular basis and clinical outcome of human papillomavirus (HPV)-positive cancer is highlighted, and the potential role of anti-EGFR target therapy for HPV-positive HNSCC is discussed. Finally, the possible mechanism for resistance to anti-EGFR target therapy is reviewed, and I discuss approaches to overcome the resistance with reference to an ongoing clinical trial.

Anti-tumoral effect of the mitochondrial target domain of Noxa delivered by an engineered Salmonella typhimurium

Bacterial cancer therapy relies on the fact that several bacterial species are capable of targeting tumor tissue and that bacteria can be genetically engineered to selectively deliver therapeutic proteins of interest to the targeted tumors. However, the challenge of bacterial cancer therapy is the release of the therapeutic proteins from the bacteria and entry of the proteins into tumor cells. This study employed an attenuated Salmonella typhimurium to selectively deliver the mitochondrial targeting domain of Noxa (MTD) as a potential therapeutic cargo protein, and examined its anti-cancer effect. To release MTD from the bacteria, a novel bacterial lysis system of phage origin was deployed. To facilitate the entry of MTD into the tumor cells, the MTD was fused to DS4.3, a novel cell-penetrating peptide (CPP) derived from a voltage-gated potassium channel (K_v2.1). The gene encoding DS4.3-MTD and the phage lysis genes were placed under the control of P_BAD, a promoter activated by L-arabinose. We demonstrated that DS4.3-MTD chimeric molecules expressed by the Salmonellae were anti-tumoral in cultured tumor cells and in mice with CT26 colon carcinoma.

Imaging of epidermal growth factor receptor expression in head and neck cancer with SPECT/CT and 111In-labeled cetuximab-F(ab')2

Combined treatment of advanced head and neck squamous cell carcinomas (HNSCC) with radiotherapy and the epidermal growth factor receptor (EGFR) inhibitor cetuximab improves clinical outcome in comparison to radiotherapy alone but is effective only in a few cases. To select those patients most likely to benefit from EGFR inhibition, it can be advantageous to quantify the tumor EGFR status before and possibly during therapy. The aim of this study was to develop and characterize the (111)In-cetuximab-F(ab')2 tracer to image EGFR targeting in vivo.

METHODS

The affinity and internalization kinetics of (111)In-cetuximab-F(ab')2 were determined in vitro. The optimal protein-fragment dose for imaging was determined in nude mice with a subcutaneous head and neck carcinoma model (FaDu). Mice with FaDu tumors were imaged using ultra-high-resolution SPECT with (111)In-cetuximab-F(ab')2 or (111)In-cetuximab IgG at 4, 24, 48, and 168 h after injection. Tumor tracer uptake was determined on micro-SPECT and autoradiography images of tumor sections. Immunohistochemical staining was used to analyze EGFR expression in the tumor.

RESULTS

In vitro, more than 50% of (111)In-cetuximab-F(ab')2 was internalized into FaDu cells within 24 h. The half maximal inhibitory concentration (IC50) of (111)In-cetuximab-F(ab')2 and (111)In-cetuximab was similar: 0.42 ± 0.16 nM versus 0.28 ± 0.14 nM, respectively. The protein dose-escalation study showed that the highest uptake of (111)In-cetuximab-F(ab')2 in tumors was obtained at doses of 10 μg/mouse or less (13.5 ± 5.2 percentage injected dose per gram [%ID/g]). Tumor uptake of (111)In-cetuximab was significantly higher (26.9 ± 3.3 %ID/g, P < 0.01). However, because of rapid blood clearance, tumor-to-blood ratios at 24 h after injection were significantly higher for (111)In-cetuximab-F(ab')2 (31.4 ± 3.8 vs. 1.7 ± 0.2, respectively; P < 0.001). The intratumoral distribution of (111)In-cetuximab-F(ab')2 correlated well with the immunohistochemical distribution of EGFR (r = 0.64 ± 0.06, P < 0.0001). micro-SPECT images of (111)In-cetuximab-F(ab')2 clearly showed preferential uptake in the tumor from 4 h onward, with superior tumor-to-background contrast at 24 h, compared with (111)In-cetuximab (107.0 ± 17.0 vs. 69.7 ± 3.9, respectively; P < 0.05).

CONCLUSION

(111)In-cetuximab-F(ab')2 displays higher tumor-to-blood ratios early after injection than (111)In-cetuximab in an HNSCC model, making it more suitable for EGFR visualization and potentially for selecting patients for treatment with EGFR inhibitors.

Anti-cancer Therapies in High Grade Gliomas

High grade gliomas represent one of the most aggressive and treatment-resistant types of human cancer, with only 1–2 years median survival rate for patients with grade IV glioma. The treatment of glioblastoma is a considerable therapeutic challenge; combination therapy targeting multiple pathways is becoming a fast growing area of research. This review offers an up-to-date perspective of the literature about current molecular therapy targets in high grade glioma, that include angiogenic signals, tyrosine kinase receptors, nodal signaling proteins and cancer stem cells related approaches. Simultaneous identification of proteomic signatures could provide biomarker panels for diagnostic and personalized treatment of different subsets of glioblastoma. Personalized medicine is starting to gain importance in clinical care, already having recorded a series of successes in several types of cancer; nonetheless, in brain tumors it is still at an early stage.

Epidermal growth factor receptor targeting in cancer: a review of trends and strategies

The epidermal growth factor receptor (EGFR) is a cell-surface receptor belonging to ErbB family of tyrosine kinase and it plays a vital role in the regulation of cell proliferation, survival and differentiation. However; EGFR is aberrantly activated by various mechanisms like receptor overexpression, mutation, ligand-dependent receptor dimerization, ligand-independent activation and is associated with development of variety of tumors. Therefore, specific EGFR inhibition is one of the key targets for cancer therapy. Two major approaches have been developed and demonstrated benefits in clinical trials for targeting EGFR; monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs). EGFR inhibitors like, cetuximab, panitumumab, etc. (mAbs) and gefitinib, erlotinib, lapatinib, etc. (TKIs) are now commercially available for treatment of variety of cancers. Recently, many other agents like peptides, nanobodies, affibodies and antisense oligonucleotide have also shown better efficacy in targeting and inhibiting EGFR. Now a days, efforts are being focused to identify molecular markers that can predict patients more likely to respond to anti-EGFR therapy; to find out combinatorial approaches with EGFR inhibitors and to bring new therapeutic agents with clinical efficacy. In this review we have outlined the role of EGFR in cancer, different types of EGFR inhibitors, preclinical and clinical status of EGFR inhibitors as well as summarized the recent efforts made in the field of molecular EGFR targeting.

Pharmacokinetics, pharmacodynamics and physiologically-based pharmacokinetic modelling of monoclonal antibodies

Development of monoclonal antibodies (mAbs) and their functional derivatives represents a growing segment of the development pipeline in the pharmaceutical industry. More than 25 mAbs and derivatives have been approved for a variety of therapeutic applications. In addition, around 500 mAbs and derivatives are currently in different stages of development. mAbs are considered to be large molecule therapeutics (in general, they are 2-3 orders of magnitude larger than small chemical molecule therapeutics), but they are not just big chemicals. These compounds demonstrate much more complex pharmacokinetic and pharmacodynamic behaviour than small molecules. Because of their large size and relatively poor membrane permeability and instability in the conditions of the gastrointestinal tract, parenteral administration is the most usual route of administration. The rate and extent of mAb distribution is very slow and depends on extravasation in tissue, distribution within the particular tissue, and degradation. Elimination primarily happens via catabolism to peptides and amino acids. Although not definitive, work has been published to define the human tissues mainly involved in the elimination of mAbs, and it seems that many cells throughout the body are involved. mAbs can be targeted against many soluble or membrane-bound targets, thus these compounds may act by a variety of mechanisms to achieve their pharmacological effect. mAbs targeting soluble antigen generally exhibit linear elimination, whereas those targeting membrane-bound antigen often exhibit non-linear elimination, mainly due to target-mediated drug disposition (TMDD). The high-affinity interaction of mAbs and their derivatives with the pharmacological target can often result in non-linear pharmacokinetics. Because of species differences (particularly due to differences in target affinity and abundance) in the pharmacokinetics and pharmacodynamics of mAbs, pharmacokinetic/pharmacodynamic modelling of mAbs has been used routinely to expedite the development of mAbs and their derivatives and has been utilized to help in the selection of appropriate dose regimens. Although modelling approaches have helped to explain variability in both pharmacokinetic and pharmacodynamic properties of these drugs, there is a clear need for more complex models to improve understanding of pharmacokinetic processes and pharmacodynamic interactions of mAbs with the immune system. There are different approaches applied to physiologically based pharmacokinetic (PBPK) modelling of mAbs and important differences between the models developed. Some key additional features that need to be accounted for in PBPK models of mAbs are neonatal Fc receptor (FcRn; an important salvage mechanism for antibodies) binding, TMDD and lymph flow. Several models have been described incorporating some or all of these features and the use of PBPK models are expected to expand over the next few years.

The effect of monoclonal antibody cetuximab (C225) in combination with tyrosine kinase inhibitor gefitinib (ZD1839) on colon cancer cell lines

AIMS

The epidermal growth factor receptor (EGFR) is abnormally activated in many tumours. Two different categories of compounds targeting EGFR, monoclonal antibodies (mAbs) and low molecular weight tyrosine kinase inhibitors (TKIs), which target extracellular and intracellular domains of the receptor, respectively, have shown antitumour activity. We decided to explore whether the combined administration of cetuximab, a mAb, and gefitinib, a TKI, had superior antitumour activity than either agent given alone.

METHODS

We studied the effects of cetuximab alone, gefitinib alone and the combination of cetuximab and gefitinib in two colon cancer cell lines, HT-29 and LoVo. The effects of these two agents on cell proliferation and induction of apoptosis were evaluated.

RESULTS

Dose-dependent activity of cetuximab alone or gefitinib alone or the combination was observed for both colon cancer cell lines. In addition, the combined treatment with cetuximab and gefitinib resulted in a synergistic and more pronounced growth effect on cell proliferation and induction of apoptosis than either single-agent treatment.

CONCLUSIONS

Our findings suggest that combined treatment with distinct EGFR inhibitory agents can augment the antitumour response over that realised with a single EGFR inhibitor. New and tempting treatment strategies on the EGFR target consisting of a double hit with a mAb and a TKI may improve the therapeutic ratio for colorectal cancer in future clinical trials.